Think Like a Rocket Scientist

�They�re all a bunch of what-iffers over there at the lab,� a Caltech professor�s wife remarked. �They might as well ask, �What if the sky should fall?� as far as I�m concerned.� Her disdain for �What-iffers� is a common reaction. People who ask a lot of questions can be quite annoying�particularly if the questions are good ones. The laboratory the lady was referring to was Caltech�s Jet Propulsion Lab�NASA�s crown jewel. The �bunch� were all the rocket scientists working there. It�s true�there is a worrywart side to rocket scientists. And for good reason: Murphy�s law. �If anything can go wrong�it will.� Learned from hard experience. Space travel, after all, is extremely hazardous. It involves riding a highly explosive rocket (essentially a fl ying bomb) into orbit, living in the space environment with its dangers of airlessness, microgravity, and radiation, and then surviving a fi ery reentry through Earth�s atmosphere. A lot can go wrong�and a lot has. You�d be a fool not to ask a lot of questions. This is not fear�it is reason. Here are some what-ifs we dealt with along the way to the moon. Question: What if the rocket blows? Answer: Use an escape system that catapults the astronauts high above the explosion and deploys parachutes to save them. Question: What if the rocket comes crashing down in a residential or tourist area near the sunny beaches of Florida? Answer: Detonate the self-destruct system�blow the rocket to kingdom come. Question: What if the Russians should get there fi rst? Answer: Build the Apollo spacecraft�but fast�and win the race. Our very survival is at stake and failure is not an option here. Question: What if Alan Shepard has to pee? Answer: Didn�t see that one coming�let him pee in his suit. Question: What if Gus Grissom has to pee? Answer: Got that one covered�put a rubber on him. Question: What if John Glenn�s heat shield should detach before or during reentry? Answer: Don�t jettison the retro-rockets�the straps may hold the shield on just long enough. (The right answer, but it turned out to be a false alarm�a faulty warning light. But it�s good for us, keeps everyone on his or her toes�especially Glenn.) Question: What if the Apollo loses power on the way to the moon? Answer: Do we have to think of everything? Oh�that�s right�we do. Use the lunar lander as a lifeboat. Good thing we thought of this�it saved the Apollo 13 crew and made a pretty good movie. (See the fi lm Apollo 13�it�s great!) We had a nice collection of what-ifs during the Apollo days. Unfortunately, over the next three decades NASA (in a sort of institutional Alzheimer disease) forgot the hard-won lessons of its youth. Consider some of these unanswered, or poorly answered, what-ifs that apply to the shuttle program. Question: What if the shuttle blows during launch? Answer: First of all that�s an unfair question, because it�s not going to happen. We estimate that the chance that a shuttle will be destroyed during a launch is 1 in 100,000 launches. Question: But, really, what if it does blow? Answer: Then the astronauts die. Question: What if the shuttle damages or loses its heat shielding before or during reentry? Answer: Again we�re talking about an extremely rare event. We estimate the odds of that happening to be infi nitesimal�zero actually. Question: But what if it does, say, lose a bunch of tiles? Answer: Then the astronauts die. Question: What if the shuttle guidance fails during reentry�say they lose power? Answer: Hasn�t happened. Question: But if? Answer: Then the astronauts die. Question: What if we keep fl ying the shuttle, knowing that it has so many failure modes? Answer: Well, space travel is not for the fainthearted. You�ve got to expect a few accidents, maybe a few fatalities. But if we didn�t accept this, then we couldn�t have a shuttle program. Question: What if we can�t get to the space station because the shuttle is too unsafe to fl y? Answer: Well, this line of questioning has been highly speculative, but if we accept this hypothetical case�then we�re talking about going to the Russians and paying them to get us to the station. Question: What if the space station didn�t exist? Answer: Then the shuttle would have nowhere to go. I hope I don�t sound too negative. Let�s add a positive note to fi nish off: Question: What if we decided not to complete the construction of the space station, but put those funds toward real space exploration? Answer: Then we would save about $100 billion, which is more than enough to send the fi rst humans to Mars!